Gas Exchange in a Georgia Salt Marsh1

The oxygen consumption of the undisturbed marsh surface, of well‐stirred mud samples, and of above‐ and below‐ground portions of Spartina was measured as were oxygen and redox profiles and sediment particle size. All but the uppermost fraction of the sediment was oxygen free and the intensity of reduction was high in all but the best drained areas and was not correlated with amount of reduced material present. The latter was, however, roughly correlated with primary productivity. The rate of energy degradation of the bacteria living in the marsh mud was increased about 25 times when they were supplied with oxygen. Spartina, the major marsh producer, consumes more oxygen than any other group. Next in importance are the bacteria of the mud.